China is planning to impose tougher restrictions on the import of soybeans after imports more than doubled during the first half of this year.

Trade sources told Reuters that Chinese quarantine authorities had given embassy officials from Argentina, Brazil and the US verbal notice of the new restrictions. These three countries are the top soy producers in the world.

Sources at the Brazilian embassy in the Chinese capital of Beijing confirmed that Chinese officials had told them that phytosanitary problems had been discovered in shipments, and that as a result measures might be taken to protect the Chinese market and the environment.

The Chinese quarantine authorities are reported to have been slow in handing out import permits in recent weeks, often leaving ships stranded offshore. Traders are quoted as saying they suspect that China is simply determined to control the market, and is using the GMO issue or alleged phytosanitary problems as a useful pretext.